Agricultural work machines, such as combines, are employed in the agricultural industry for various tasks, including harvesting crops. During harvesting operations, typical such agricultural work machines move through a crop field while operating a header at the front of the work machine, to cut or gather the crop. The agricultural product, e.g., grain, is then removed from the non-grain crop materials by threshing, separating and cleaning assemblies on the work machine, and then the grain is transferred to the work machine's hopper for temporary storage.
At various times during harvesting operations, such as when the work machine's hopper is full, the operator of the work machine will unload the agricultural product from the work machine using a cantilevered unloading system that is mounted on the work machine. Typically, the agricultural product is unloaded via the unloading system into a mobile agricultural product carrier, such as a tractor pulled hopper wagon (grain cart), a truck, or a tractor-frailer, which delivers the agricultural product to a storage facility or to another transport system. At times, the mobile agricultural product carrier may travel beside the work machine during simultaneous harvesting and unloading operations. Typically, the cantilevered unloading system pivots to swing away from a stowed position to a fixed pivot position, and some systems may be manually adjusted from the fixed pivot position with respect to the fore/aft (lengthwise) position of the unloading point. However, this arrangement limits an operator's ability to compensate for different grain cart sizes or header widths.
An unloading system as described above typically includes an unloading auger or and unloading conveyor. Unloading augers are more common, while unloading belt conveyors are becoming more common since they have a higher flow rate capacity which can be important with the ever increasing size of harvesters. Regardless of whether the unloading system is an auger or belt conveyor based system, the inlet end is submersed in the grain and the unloading operation takes place at full rate all of the time. There is no way to control the unload rate, and thus as crops and conditions change, the true unload rate varies and cannot be adjusted. If the unload rate is too high, then overloading of the unloading system structure can occur, especially in long and ultra-light unloading systems. This is especially true in rough ground, where undue forces can be applied to the cantilevered unloading system. On the other hand, as the size of harvesters continue to increase, a decreased unload rate which is under the capacity of the unloading system can result in decreased productivity and loss of profit.
What is needed in the art is an unloading system for an agricultural harvester which allows the unloading system to be run at maximum capacity, while avoiding physical damage to the unloading system from an overload condition.